Random Number Generator

Generate cryptographically secure random numbers in any range. Set the count, decimal places, and optionally prevent duplicates — then copy or download your results.

How Random Numbers Are Generated

This tool uses crypto.getRandomValues() — the browser's Web Crypto API — to generate random numbers. Unlike Math.random(), which uses a deterministic algorithm, the Web Crypto API is seeded by the operating system's entropy pool (hardware events, interrupt timing, and other unpredictable sources). This makes the output genuinely unpredictable and suitable for security-sensitive applications.

Use Cases

• Lottery and raffle draws: Enable no-duplicates and set your number range
• Statistical sampling: Generate random samples from a population range
• Games and simulations: Dice rolls, card draws, random events
• Random ordering: Generate unique numbers to shuffle a list
• Testing and development: Seed data, random IDs, test inputs
• Decision making: Pick a random number to break a tie or make a choice

Integers vs Decimals

Set Decimal places to 0 to generate whole integers. Increase it to generate floating-point numbers with up to 10 decimal places. For example:

• Min: 1, Max: 6, Decimals: 0 → simulates a dice roll
• Min: 0, Max: 1, Decimals: 4 → random probability between 0 and 1
• Min: 0, Max: 100, Decimals: 2 → random percentage with two decimal places

No Duplicates Mode

When "No duplicates" is enabled, the generator uses a Fisher–Yates shuffle over the integer range to ensure each number appears at most once. This requires:

• Integer mode (decimal places = 0)
• Count ≤ (Max − Min + 1)

This is ideal for lottery picks, random sampling without replacement, or generating unique IDs within a bounded range.

Frequently Asked Questions